Hydraulic pump



Feb. 22, 1966 c, H s Y 3,236,566

HYDRAULIC PUMP Filed March 20, 1963 4 Sheets-Sheet l INVENTOR. Jam; 6', flake BY HM 'h Feb. 22, 1966 D. c. HALSEY 3,236,566

HYDRAULIC PUMP Filod March 20, 1963 4 Sheets-Sheet 2 INVENTOR. QE-EE- Jaw a. y.

D. C. HALSEY HYDRAULIC PUMP Feb. 22, 1966 4 Sheets-Sheet 5 Filed March 20, 1965 INVENTOR. flax 227 6', fllzs'ey //LZL1LL L lq K Q LLJ Feb. 22, 1966 D. c. HALSEY 3,

HYDRAULIC PUMP Filed March 20, 1963 4 Sheets-Sheet 4.

United States Patent O 3,236,566 HYDRAULIC PUMP David C. Halsey, Birmingham, Mich., assignor to Chrysler Corporation, Highland Park, Mich., a corporation of Delaware Filed Mar. 20, 1963, Ser. No. 266,569 9 Claims. (Cl. 1032) This invention relates to improvements in hydraulic pumps, particularly high pressure pumps suitable for use with automobile power steering mechanisms.

An important object of the present invention is to provide an improved balanced pump of the above character comprising a housing containing a cylindrical pumping cam of out-of-round cross section. A cylindrical rotor mounted within the cam cooperates with the latter to provide a pair of diametrically spaced inlet chambers and another pair of diametrically spaced pumping chambers associated respectively with corresponding pairs of inlet and pumping arcs at the inner surface of the cam. The rotor carries a plurality of radially shiftable pumping elements such as slippers or rollers in fluid pumping and sealing engagement with the inner cylindrical surface of the cam, which latter also comprises a separate constant radius dwell or sealing arc spacing each pair of proximate ends of the pumping and inlet arcs and has a pair of inlet ports extending radially through its sidewall to connect the two inlet chambers with an annular fluid inlet header extending coaxially around the outer surface of the cylindrical cam.

By virtue of the annular inlet header enclosing the outer surface of the cam, free interchange of fluid between the inlet ports and also the supply of fluid to both inlet ports are readily accomplished regardless of constantly changing pump speeds. In consequence, means are avoided for prorating the inlet fluid to the two inlet chambers, as for example by varying the size of the radial inlet ports. The provision of the annular inlet header also renders the pump suitable for use with either an odd or even number of pumping elements without necessitating any change in the dimensions of the cam or ports or other features of the pump.

Another object is to provide such a pump wherein the inlet ports are located to assure a predetermined circulation of fluid in the inlet header, thereby to stabilize the temperature around the periphery of the cam to achieve efficient operation of the pump and reduction in noise by minmimizing localized differential heating and consequent warping of the pump elements.

Other objects are to provide an improved compact arrangement in an automobile power steering pump and flow control valve for regulating the rate of flow of pressurized fluid from the pump to the power steering motor, which is particularly efficient in operation, simple in construction, economical to manufacture and assemble and has a compact simplified housing adapted to be readily fabricated by casting and broaching operations.

Another object is to provide a pump and flow control valve combination wherein, in cooperation with the radial inlet ports, a pair of axial discharge ports are provided in the housing in communication with the pumping chambers respectively. The discharge ports extend to an annular discharge header coaxial with the rotor and spaced axially therefrom. The flow control valve comprises an annular spool shiftable axially in a bypass bore in the housing parallel and adjacent to the axis of the pump rotor. The annular discharge header of the pump is in communciation with the bypass bore at an upstream end of the valve spool, the bypass bore being also in communication with the annular inlet header downstream of the valve spool by means of a radial conduit in the pump housing.

In accordance with the above described arrangement of the radial inlet ports and axial discharge ports, the sealing between these ports as well as the arrangement of the porting itself is greatly simplified and radial loading of the bearings for the rotor is minimized. In addition the employment of the annular discharge header coaxially with the rotor enhances the advantages achieved by the annular inlet header. The arrangement of the bypass bore parallel to the rotor and the connection between the bypass bore and the annular discharge header simplifies the porting for the bypass valve and enables the use of a single-land spool valve.

Another object is to provide such a combination Wherein the radial conduit connecting the bypass bore and annular inlet header is provided with a venturi restriction into which opens an axially extending passage from a fluid reservoir, whereby fluid from the power steering motor is returned to the reservoir and is then supercharged into the annular inlet header under pressure by virtue of the radial flow of fluid through the venturi restriction from the bypass port.

Another object is to provide an improved hydraulic pump comprising a cast steel housing body having a large intermediate chamber containing the cam and rotor and opening axially in opposite directions into smaller coaxial bores. One of the smaller bores extends through a thickened load supporting portion of the housing body and carries a journal for a coaxial rotor shaft on which is keyed a power driven pulley. One axial end of the cam is supported for axial sliding movement within the other of the smaller bores which is sealed exteriorly of the cam by an end closure comprising a fixed outer plug and an axially slidable inner pressure plate. The plug and plate cooperate to provide the aforesaid annular discharge header therebetween, whereby the pressure plate is urged axially into abutment with an axial end surface of the cam by the fluid pressure within the discharge header. The axial end of the cam opposite the pressure plate is spaced from the housing body by a wear plate, the pressure plate, cam, and wear plate being supported for axial sliding movement and maintained in assembled relationship by a plurality of pins extending axially therethrough and secured at their opposite ends within the plug and housing body.

In accordance with the foregoing, the discharge header is conveniently contained within the bore at one axial end of the housing body between the end closure members for that bore, the fluid pressure in the discharge header serving to maintain certain of the working parts of the pump in axial abutment with a force proportional to the pump discharge pressure. In consequence, leakage between these parts is minimized when the pump is under load and operating at high pressure, whereas wearing between these parts is minimized when the pump is operating at low pressure, even though at high speed.

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

FIGURE 1 is an axial section of a pump embodying the present invention taken in the direction of the arrows substantially along the line 1-1 of FIGURE 3.

FIGURE 2 is a reduced transverse sectional view with reservoir cover removed, taken in the direction of the arrows substantially along the line 22 of FIGURE 1.

FIGURE 3 is a sectional view taken in the direction of the arrows substantially along the line 33 of FIGURE 1.

FIGURE 4 is a fragmentary sectional view taken in the direction of the arrows substantially along the line 4--4 of FIGURE 3.

FIGURE 5 is a right end view of the pump illustrated in FIGURE 1 with the pulley removed.

FIGURE 6 is a fragmentary sectional view taken in the direction of the arrows substantially along the line 66 of FIGURE 5.

FIGURE 7 is a reduced transverse sectional view through the pumping cam element, illustrating the inlet and pumping arcs spaced by the constant radii dwell arcs.

It is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraselogy or terminology employed herein is for the purpose of description and not of limitation.

Referring to the drawings, an embodiment of the present invention is illustrated by way of example comprising a cast steel housing 10 having a large bore 11 opening at one end and a smaller coaxial bore 12 opening at the opposite end through a thickened portion 10a of the housing. The bores 11 and 12 open inwardly into an enlarged intermeditae chamber 13 containing a hollow cylindrical cam 14 having an outer cylindrical surface closely confined at one end Within bore 11. A rotor 15 coaxial with the outer surface of cam 14 is contained within the hollow cam and is splined on a central rotor shaft 16 coaxial with the bores 11 and 12 so as to rotate with shaft 16 and slide axially thereon. Extending coaxially in opposite directions from the rotor 15 are bearing portions 16a and 16b of the shaft 16 journaled within bearings 17 and 18 respectively, the latter bearing being supported within the housing portion 10a which is adapted to withstand the major side loading of the bearing 18 resulting from operation of the pump under load. The shaft extension 1617 projects outwardly through a suitable seal 19 contained within housing portion 10a and is keyed to the hub 20 of a power driven pulley 21.

The interior cylindrical surface of cam 14 is out of round and cooperates with rotor 15 to provide a pair of diametrically opposed inlet chambers 22 and a pair of diametrically opposed pumping or discharge chambers 23 mutually spacing each other, FIGURE 2. The periphery of rotor 15 is provided with a plurality of cylindrical axially extending and radially outwardly opening notches 24 for a corresponding number of cylindrical rollers 25 of circular cross section. The present pump is designed to employ approximately eleven or twelve rollers 25 which make sliding and sealing engagement with the interior surface of cam 14 and with the trailing surface of the associated notch 24 in consequence of the fluid pressure and centrifugal and inertia forces acting thereon during operation of the pump.

The opposite axial ends of cam 14 and rotor 15 as well as the axially inner surface of housing portion 10a lie in transverse planes perpendicular to the rotor axis, the right ends of cam 14 and rotor 15 being spaced from housing portion 10a by an annular wear plate 26 having the same outside diameter as cam 14. The outer surfaces of cam 14 and wear plate 26 are spaced from the inner circumference wall of housing 10 to provide an annular inlet header 27 extending coaxially around the axis of rotor shaft 16 and communicating with the inlet chambers 22 via a corresponding pair of inlet ports 28 extending generally radially through cam 14.

The bore 11 at the left end of housing 11 is provided with a closure including an annular pressure plate 29 having a plane axial inner end surface abutting the left end of cam 14 and having an outer cylindrical surface closely fitting within bore 11 in sliding relation. The closure for bore 11 also includes an annular cap or closure member 30 seated on an annular axial extension 31 of plate 29. Suitable annular seals 32 and 32a between the juxtaposed surfaces of extension 31 and cap 30 and also between cap 30 and the inner Wall of b re 11. prevent axial loss of pressurized fluid between these members. The confronting surfaces of plate 29 and cap 30 are formed with mating grooves 33 and 34 which cooperate to provide an annular discharge header extending coaxially around the axis of rotor shaft 16 and communicating with the discharge chambers 23 via a corresponding pair of discharge ports 38 extending axially through plate 29. A coil spring 35 within the header 33, 34 urges plate 29 to the right toward the end surfaces of cam 14 and rotor 15. Leftward movement of cap 30 is prevented by an annular snap ring 36 partially embedded within the interior surface of bore 11.

A pair of diametrically spaced locating dowels 37, FIG- URES 2 and 4, extend slidably through plate 219, cam 14 and wear plate 26 and are confined at their axially opposite ends in housing portion 10a and cap closure 30. Thus fluid pressure within discharge header 33, 34 urges members 29, 14 and 26 closely together and toward the inner wall of housing portion 10a to prevent fluid leakage between these parts with a force proportional to the pump discharge pressure, which force is also proportional to the tendency for fluid leakage. At the same time, thermally induced dimensional changes in these parts, particularly between cam 14 and rotor 15, is readily accommodated. Furthermore, the axial dimension of rotor 15 and cam 14 may feasibly be almost identical to achieve optimum pump efficiency by minimizing a bypass flow of fluid around the ends of the rotor 15 during operation of the pump. Also in accordance with the construction shown and as explained more fully below, axially directed forces on the cam 14 and rotor shaft 16 are substantially in balance at all times. Small transient unbalanced forces are assumed by the annular thrust bearing 39 having its inner circumference closely confined within a mating groove in shaft 16 and having an outer portion confined between plate 26 and housing portion 10a.

Extending radially from bore 11 and header 27 is an extension 101) of the housing 10 which contains a bypass bore 40 parallel to the coaxial bores 11 and 12. An axially slidable single-land spool valve 41 within bore 40 normally closes a supply conduit 42 extending radially inwardly from a central portion of bore 40 into the inlet header 27. The valve 41 has a hollow interior 43 opening to the right in FIGURE 1 and containing a coil spring 44 under compression between a closure plug 45 and the left end of the interior 43. The closure 45 seals the right end of bore 40, which extends completely through hous ing extension 1012, and is retained against rightward movement by snap ring 46 embedded within the interior wall of bore 40. The left end of valve 41 is reduced at 47 to provide a radial shoulder 48 and contains four radial metering ports 49 opening into the interior 43 of valve 41. The left end of bore 40 is closed by a closure plug 50 retained against leftward movement by snap ring 51 partially embedded within the inner Wall of bore 40. The plug also provides an integral axially inwardly directed stop 52 which abuts valve 41 to limit its leftward movement.

Pressurized fluid from discharge header 33, 34 is conducted by a generally radially extending duct 53 in housing 10, FIGURE 3, to an enlargement 54 of bore 40 at the left end of valve 41. Pressurized fluid from conduit 53 enter-s the left end of bore 40 at the enlargement 54, then flows through metering orifices 49 at a substantially constant rate of approximately two gallons per minute into the interior 43 then to an enlargement 55a at the right end of bore 40, from whence the metered fluid is conducted via transverse duct 55 to duct 56 within housing 10 and an exterior conduit 57 to the vehicle; power steering unit, FIGS. 5 and 6.

Extending around the circumference of the housing 1% is an annular grooved support 58 on which is supported the flanged end 59 of a cup shaped container 60. The latter encloses the left end of housing 10 and cooperates. therewith to form a reservoir 61 into which the fluid from the power steering unit may be returned. Fluid leakage between the support 5'8 and the juxtaposed side walls of the container 60 is prevented by an O-ring 62.

In order to supercharge the flow of fluid into the inlet header 27 via supply conduit 42, the latter is provided with a venturi restriction 63 at the opening of a duct 64 in communication with the reservoir 61. The bypass bore enlargement 55a and transverse duct 55 are also connected by means of a pressure relief conduit 65 in housing portion 1012 with an axially extending threaded conduit 66 opening into the reservoir 61 and normally closed by a pressure relief valve 67 which may be of conventional construction.

In operation of the structure described, upon the application of power to pulley 21, rotor is rotated in the direction of the arrow, FIGURE 2, to draw fluid into the inlet chambers 22 from header 27 via the radial inlet ports 28 by operation of the rollers 25. The fluid drawn into the inlet chambers 22 is carried clockwise to the discharge chambers 23 and is then forced into the discharge header 33-, 34 via the axial discharge ports 38. In order to balance the pump hydraulically, axially inwardly opening notches 68 shaped identically with the discharge ports 38 are formed in the surface of the wear plate 26. Small tapered precompression notches 28a and 38a are provided at the trailing edges of the inlet ports 28 and in the leading edges of the discharge ports 38 to accommodate inertial efiects of the fluid and to minimize cavitation and noise during pump operation in accordance with customary practice. Also by the construction described, leakage from discharge header 33, 34 returns to inlet header 27. Endwise leakage at bearing 17 returns to the reservoir 60. Endwise leakage at bearing 18 is collected in annular chamber 69 upstream of seal 19 and is returned via duct 70 to inlet header 27.

As the discharge pressure increases at high pump load, as for example during a parking maneuver when the pump is normally operating at low speed, the resulting high pressure in discharge header 33, 34 urges pressure plate 29 more firmly toward the juxtaposed ends of cam 14 and rotor 15 to compact these members more tightly between plates 26 and 29 than when the pump is under light load, as for example during straight ahead steering when the pump is usually operating at high speed. The high pressure fluid discharged from header 33, 34 is conducted via conduit 53 to the inlet or upstream end 54 of bypass bore 40, whereby fluid at the rate of approximately two gallons per minute is supplied to the power steering unit via metering ports 49 as described above. The pressure of the pump discharge in excess of the two gallons per minute flow will act on the left end of valve 41 to move the latter rightward against the tension of spring 44 until shoulder 48 establishes communication between supply conduit 42 and the upstream inlet enlargement 54. The pressure at which valve 41 opens to bypass the pump discharge into supply conduit 42 will of course be determined by the tension of spring 44. In the event that the pump discharge pressure exceeds a predetermined limit downstream of ports 29, pressure relief valve 67 will open to discharge directly from duct 55 into reservoir 61.

During normal operation of the pump, the bypass flow from enlargement 54 into supply conduit 42 will result in a reduced pressure at the venturi 63 whereby the flow of fluid from reservoir 61 through duct 64 and into inlet header 27 will be accelerated to supercharge the flow to the inlet ports 28. In this regard it is to be noted that the opening of duct 64 into supply conduit 42 is adjacent the juncture of the latter with inlet header 27 to assure optimum supercharging. Also the two diametrically opposed inlet ports 28 are arranged "asymmetrically with respect to the supply conduit 42, the port 28 which is located on the clockwise side of duct 42, FIGURE 2, being more remote than the diametrically opposed inlet port 28, so that these two ports may both be of the same size and yet receive the same amounts of inlet fluid. The length of the path of the inlet flow in header 27 to the inlet port 28 in the same clockwise direction as the rotation of rotor 15 is determined with respect to the length of the path of the corresponding inlet flow in the opposite direction to the other inlet port 28 so that the amount of flow to each inlet port 28 from supply conduit 42 is approximately balanced. The ports 28 are located however so that a portion of the inlet flow into the port 28 at the counterclockwise side of supply conduit 42 will enter in a clockwise direction from the far side of the inlet header 27. The amount of such flow will vary in accordance with the speed of rotation of the pump, but will always be adequate to prevent stagnation of fluid within the far side of the inlet header 27 In consequence of the arrangement described, the fluid flow within header 27 will serve as a coolant to minimize localized overheating of the pump and assure a more uniform thermal expansion and contraction of its parts. In addition, a portion of the header 27 connecting the inlet ports 28 at the side of the header opposite the supply conduit 42 assures fluid supply to both ports 28 and enables the use of the same cam element 14 and inlet ports 28 with a rotor having either eleven or twelve pumping elements 25.

Referring to FIGURE 7, the contour of the interior cam surface of cam element 14 is illustrated where points I and I designate the beginning and end of a fluid inlet arc I 1 along which the rollers 25 rise or move radially outwardly a total radial distance H from the circumference of a circle of small radius C to the circumference of a concentric circle of larger radius C The are I 1 represents a second inlet arc, whereas the arcs D D and D D represent first and second pumping arcs along which the rollers 25 fall the radial distance H, the arcs D I and D I represent dwell arcs of constant radius C and the arcs I D and I D represent dwell arcs of constant radius C As the rollers 25 rise along each inlet arc I 1 and I 1 upon clockwise rotation of the rotor 15, fluid is drawn through the associated inlet port 28 into the inlet chambers 22 comprising the spaces between the rotor 15 and each inlet arc. The fluid is then carried clockwise along the length of the dwell arcs I D and I D and, thereafter as the rollers fall along each pumping arc D D and D D is forced outwardly through the discharge ports 38 from the pumping chambers 23 comprising the spaces between the rotor 15 and each pumping arc.

Having thus described my invention, I claim:

1. In a fluid pump, a housing, a rotor rotatable Within said housing, a cam element extending around said rotor and cooperating therewith to provide two pumping chambers and two inlet chambers mutually spacing each other circumferentially, an inlet header extending around the circumference of said element between the latter and said housing, a pair of circumferentially spaced inlet ports extending from said inlet header generally radially through said element into said inlet chambers respectively, a pair of circumferentially spaced discharge ports opening axially into said pumping chambers respectively to receive pressurized fluid therefrom, a plurality of pumping members carried by said rotor and engaging said cam element to effect fluid seals between each discharge port and said inlet ports and also to pump fluid from each inlet port to the next successive discharge port in the direction of rotation of said rotor, each feature of said ca-m element and each inlet and discharge port being duplicated by a diametrically opposite feature to effect two identical diametrically opposed pump systems measured with respect to any diameter in said direction of rotation, and means to assure substantially equal supply of fluid to each inlet port from said inlet header comprising a fluid supply port opening into said inlet header at a location asymmetric with respect to said inlet ports, the circumferential distance from said supply port measured in said direction of rotation to the next adjacent inlet port being greater than the circumferential distance from said supply port to the other inlet port measured in the opposite direction.

2. In a fluid pump, a housing having coaxial bores at opposite ends opening inwardly into a larger intermediate chamber, a hollow cylindrical cam having one axial end slidably supported within one of said bores and projecting therefrom into said intermediate chamber, a rotor rotatable within said cam and cooperating with the latters interior wall to provide inlet and pumping chambers, a plurality of pumping members carried by said rotor in fluid pumping relationship with said interior wall, means within said one bore for closing the same including a fixed outer plug and an axially slidable pressure plate, said pressure plate cooperating with said plug to provide a fluid discharge header therebetween and being responsive to the fluid pressure in said discharge header to be urged thereby into abutment with said one axial end of said c am, the other of said bores providing a bearing support, a rotor shaft journaled in said bearing support and secured to said rotor to rotate the same, said cam being spaced from the interior wall of said intermediate chamber to provide an annular inlet header around the axis of said bores, said inlet and pumping chambers being in communication with said inlet and discharge headers respectively by inlet and discharge ports extending radially and axially respectively through said cam and pressure plate.

3. In a fluid pump, a housing, cam means in said housing defining a pump cavity, said housing having a pair of coaxial openings spaced by and communicating with said cavity, inlet and outlets ports communicating with said cavity to supply fluid thereto and to discharge fluid therefrom respectively, pumping means in said cavity for pumping said fluid from said inlet port to said discharge port including a rotor shaft having oppositely directed end portions extending coaxially into said openings respectively, means providing a bearing support for one of said rotor end portions within one of said openings, a pressure plate slidable axially within the other of said openings, said pressure plate having annular portions providing a bearing support for the other of said rotor end portions and abutting said cam means, an outer closure member for said other opening and secured therein axially endwise of said pressure plate and cooperating therewith to define a discharge header therebetween, and means connecting the fluid pressure at said discharge port with said discharge header to urge said axially slidable pressure plate against said cam means with a force proportional to the discharge pressure of said pump.

4. In a fluid pump, a housing, cam means in said housing defining a pump cavity, said housing having a pair of coaxial openings spaced by and communicating with said cavity, inlet and outlet ports communicating with said cavity to supply fluid thereto and to discharge fluid therefrom respectively, pumping means in said cavity for pumping said fluid from said inlet port to said discharge port including a rotor shaft having oppositely directed end portions extending coaxially into said openings respective- 1y, means providing a bearing support for one of said rotor end portions within one of said openings, a pressure plate slid-able axially within the other of said openings and abutting said cam means, said pressure plate having an annular bearing portion providing a bearing support for the other of said rotor end portions, an annular outer closure member for said other opening secured therein axially endwise of said pressure plate and cooperating with said annular bearing portion to define an annular discharge header between said pressure plate and closure member around the axis of said rotor, and means connecting the fluid pressure at said discharge port with said discharge header to urge said axially slidable pressure plate against said cam means with a force proportional to the discharge pressure of said pump.

5. In a fluid pump, a housing, a rotor rotatable within said housing, a cam element extending around said rotor and cooperating therewith to provide two pumping chambers and two inlet chambers mutually spacing each other circumferentially, an inlet header extending around the circumference of said element between the latter and said housing, a pair of circumferentially spaced inlet ports extending from said inlet header generally radially through said element into said inlet chambers respectively, a pair of circumferentially spaced discharge ports opening into said pumping chambers respectively to receive pressurized fluid therefrom, means carried by said rotor and cooperable with said cam element and the pumping and inlet chambers thereof to pump fluid from each inlet port to the next successive discharge port in the direction of rotation of said rotor, each feature of said cam element and each inlet and discharge port being duplicated by a diametrically opposite feature to effect two identical diametrically opposed pump systems measured with respect to any diameter in said direction of rotation, and means to assure substantially equal supply of fluid to each inlet port from said inlet header and a limited circulation of fluid in said direction of rotation within one-half of said inlet header from one inlet port to the other comprising a fluid supply port opening into the other half of said inlet header at a location asymmetric with respect to said inlet ports, the circumferential distance from said supply port measured in said direction of rotation to the next adjacent inlet port being greater than the circumferential distance from said supply port to the other inlet port measured in the opposite direction.

6. In a fluid pump, a housing having an intermediate chamber and a pair of coaxial openings spaced by and communicating with said chamber, a rotor rotatable Within said chamber having a shaft extending in one axial direction from said rotor into one of said openings and journal ed therein, a cam element extending around said rotor and cooperating therewith to provide circumferentially spaced pumping and inlet chambers, said housing being spaced from said cam element at the region of said intermediate chamber to provide an annular inlet header extending around the circumference of said element and disposed in part between the latter and said housing, an inlet port connecting said inlet header with said inlet chamber, a discharge port opening into said pumping chamber to receive pressurized fluid therefrom, a plurality of pumping members carried by said rotor and engaging said cam element to effect fluid seals between said discharge and inlet ports and also to pump fluid from said inlet port to said discharge port in the direction of rotation of said rotor, a discharge header in the other of said openings, said discharge port opening into said discharge header to discharge pressurized fluid thereinto, said inlet header having an annular axial extension in said one axial direction partially overlapping said one opening, and a drain duct in said housing connecting said one opening with said axial extension of said inlet header.

7. In a pump according to claim 6, a bypass connection between said discharge header and inlet header, bypass valve means in said bypass connection and responsive to the pressure in said discharge header for selectively controlling fluid flow from said discharge header to said inlet header, said bypass connection opening into said inlet header at a location generally diametrically opposite the opening of said drain duct into said axial extension of said inlet header.

8. In a fluid pump, a housing, cam means in said housing defining a pump cavity, said housing having a pair of coaxial openings spaced by and communicating with said cavity, inlet and outlet ports communicating with said cavity to supply fluid thereto and to discharge fluid therefrom respectively, pumping means in said cavity for pumping said fluid from said inlet port to said discharge port including a rotor shaft having oppositely directed end portions extending coaxially into said openings respectively, means providing a bearing support for one of said rotor end portions within one of said openings, a pressure plate slidable axially within the other of said openings and abutting said cam means, said pressure plate having an annular bearing portion providing a bearing support for the other of said rotor end portions, an annular outer closure member for said other opening secured therein axially endwise of said pressure plate and cooperating with said annular bearing portion to define an annular discharge header between said pressure plate and closure member around the axis of said rotor, and means connecting the fluid pressure at said discharge port with said discharge header to urge said axially slidable pressure plate against said cam means with a force proportional to the discharge pressure of said pump, a container mounted on said housing and enclosing the portion thereof having said other opening, said container cooperating with the exterior of said housing to define a reservoir chamber, said annular bearing support and outer closure member defining a fluid flow path communicating with said other rotor end portion and with said reservoir to drain fluid leaking axially endwise around said other rotor end portion.

9. In a fluid pump, a housing, cam means in said housing defining a pump cavity, a pair of coaxial openings spaced by and communicating with said cavity, inlet and outlet ports communicating with said cavity to supply fluid thereto and to discharge fluid therefrom respectively, pumping means in said cavity for pumping said fluid from said inlet port to said discharge port including a rotor shaft having oppositely directed end portions extending coaxially into said openings respectively, means providing a bearing support for one of said rotor end portions within one of said openings, means for closing the other of said openings and providing a bearing support for the other of said rotor end portions within said other opening including an axially slidable pressure plate having annular portions coaxial with said rotor and abutting said cam means and also including an outer closure member secured within said other opening axially outwardly of said pressure plate, said pressure plate and closure member cooperating to define an annular discharge header therebetween extending around the axis of said rotor shaft within said other opening, and means connecting the fluid pressure at said discharge port with said discharge header to urge said axially slidable pressure plate against said cam means with a force proportional to the discharge pressure of said pump.

References Cited by the Examiner UNITED STATES PATENTS 2,387,761 10/1945 Kendrick 103-2 X 2,696,787 12/1954 Jaworowski et a1 103-42 2,724,335 11/1955 Eames 103-42 X 2,746,391 5/1956 Jaworowski et al 103-42 2,746,392 5/1956 Klessig et al. 103-42 2,755,741 7/1956 Erskine 103-42 2,759,423 8/1956 Keel 103-42 X 2,800,083 7/1957 Tweedale et al 103-42 2,818,813 1/1958 Pettibone et a1 103-42 2,821,140 1/1958 Pettibone 103-42 2,835,201 5/1958 Pettibone 103-42 2,858,766 11/1958 Toschkoif 103-42 2,924,178 2/1960 Hogan 103-2 2,984,186 5/1961 Livermore et al. 103-42 2,996,013 8/1961 Thompson et al. 103-42 3,002,461 10/1961 Eames 103-42 3,059,580 10/1962 Farrell et al 103-42 3,076,414 2/1963 Adams 103-42 X 3,125,028 3/1964 Rhode 103-42 MARK NEWMAN, Primary Examiner.

RICHARD B. WILKINSON, Examiner. 

1. IN A FLUID PUMP, A HOUSING, A ROTOR ROTATABLE WITHIN SAID HOUSING, A CAM ELEMENT EXTENDING AROUND SAID ROTOR AND COOPERATING THEREWITH TO PROVIDE TWO PUMPING CHAMBERS AND TWO INLET CHAMBERS MUTUALLY SPACING EACH OTHER CIRCUMFERENTIALLY, AN INLET HEADER EXTENDING AROUND THE CIRCUMFERENCE OF SAID ELEMENT BETWEEN THE LATTER AND SAID HOUSING, A PAIR OF CIRCUMFERENTIALLY SPACED INLET PORTS EXTENDING FROM SAID INLET HEADER GENERALLY RADIALLY THROUGH SAID ELEMENT INTO SAID INLET CHAMBERS RESPECTIVELY, A PAIR OF CIRCUMFERENTIALLY SPACED DISCHARGE PORTS OPENING AXIALLY INTO SAID PUMPING CHAMBERS RESPECTIVELY TO RECEIVE PRESSURIZED FLUID THEREFROM, A PLURALITY OF PUMPING MEMBERS CARRIED BY SAID ROTOR AND ENGAGING SAID CAM ELEMENT TO EFFECT PORTS AND ALSO TO PUMP FLUID FROM EACH INLET PORT TO INLET PORTS AND ALSO TO PUMP FLUID FROM EACH INLET PORT TO THE NEXT SUCCESSIVE DISCHARGE PORT IN THE DIRECTION OF ROTATION OF SAID ROTOR, EACH FEATURE OF SAID CAM ELEMENT AND EACH INLET AND DISCHARGE PORT BEING DUPLICATED BY A DIAMETRICALLY OPPOSITE FEATURE TO EFFECT TWO IDENTICAL DIAMETRICALLY OPPOSED PUMP SYSTEMS MEASURED WITH RESPECT TO ANY DIAMETER IN SAID DIRCTION OF ROTATION, AND MEANS TO ASSURE SUBSTANTIALLY EQUAL SUPPLY OF FLUID TO EACH INLET PORT FROM SAID INLET HEADER COMPRISING A FLUID SUPPLY PORT OPENING INTO SAID INLET HEADER AT A LOCATION ASYMMETRIC WITH RESPECT TO SAID INLET PORTS, THE CIRCUMFERENTIAL DISTANCE FROM SAID SUPPLY PORT MEASURED IN SAID DIRECTION OF ROTATION TO THE NEXT ADJACENT INLET PORT BEING GREATER THAN THE CIRCUMFERENTIAL DISTANCE FROM SAID SUPPLY PORT TO THE OTHER INLET PORT MEASURED IN THE OPPOSITE DIRECTION. 